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What are J2EE and J2EE Application Servers? |
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J2EE is the short name for "Java 2 Enterprise Edition". Usually J2EE applications are client-server or server-side applications that require a so-called "J2EE Application Server". Many enterprise applications (ERP, CRM, complex websites) are developed in the programming language Java.
While there are ordinary Java desktop applications as well, J2EE offers various benefits like: - applications can easily be divided into client-side (running on a desktop PC) and server-side components running on a J2EE-compliant application server.
- applications can run server-side only, having a client interface that is displayed with a web browser
- client-server-communication is handled by J2EE components
- developers benefit from many services provided by J2EE-compliant application servers (they don't have to write tons of common functionality from scratch)
Commonly 2 types of "J2EE application servers" are distinguished: - Web Application Servers - only support the web-tier (layer) of J2EE which includes, "Servlets", "JavaServer Pages, JSP", etc.
- Fully compliant J2EE Application Servers - support the full J2EE stack/specification with features like "Enterprise Java Beans, EJB", etc.
| Web Application Servers | Fully compliant J2EE Application Servers | | Apache Tomcat | Apache Geronimo | | Jetty | JBoss Application Server | | | JOnAS | | | BEA Weblogic | | | Borland Enterprise Server | | ... | ... |
An application server comparison matrix can be found at: http://www.theserverside.com/reviews/matrix.tss Example of a J2EE application:
xinco DMS (http://www.xinco.org) conists of a Java client application which can a access one or many xinco DMS servers. The client application is not a J2EE application, only a simple Java Standard Edition (J2SE) installation is required on a client PC. It communicates with the server application over web-services.
The xinco DMS server application uses JavaServer Pages and Servlets for a browser-based administration interface and the web-service interface. It ONLY uses J2EE features that belong to the web-tier of J2EE.
Therefore the server application only requires a Web Application Server like Apache Tomcat!
If other J2EE features like EJB were used, a fully compliant J2EE application server like JBoss AS would be required instead! |
